A brief introduction to testosterone and its properties and benefits

Testosterone is the most important male sex hormone responsible for correctly functioning multiple body processes.

This anabolic steroid is directly involved in developing reproductive organs in men and developing secondary male sexual characteristics.

Testosterone plays a vital role in the lives of women, too.

Inadequate testosterone amounts can lead to numerous health issues, such as low bone density (and susceptibility to fractures), poor sex drive, and lack of concentration.

Normal testosterone levels in men are between 300 ng/dL and 1,000 ng/dL.

Normal testosterone levels in women are usually between 15 ng/dL and 70 ng/dL. This number varies depending on various factors such as the moment of the day, mood, diet, exercise level, and more.

However, certain men might have low testosterone levels (under 350 ng/dL) and experience symptoms such as fatigue, lack of sexual desire, and developing male breasts (gynecomastia).

Testosterone replacement therapy might be helpful for men who have low testosterone blood levels. This treatment will help raise testosterone levels to average values.

Inadequate testosterone amounts can also impair muscle development and slow one’s progress in the gym. Men usually have 40 times more testosterone than women, and keeping T levels in the normal range is essential to ensuring proper muscle growth.

Declining testosterone levels in men over 45 are typical and often cause erectile dysfunction (ED). Androgen deficiency, or hypogonadism, affects roughly 40% of men aged 45 or older.  Two-thirds of these men present with symptoms. While some symptoms, like ED, indicate a deficiency, additional symptoms can be similar to those of other diseases, such as cardiovascular disease. 

What is hypogonadism?  

Male hypogonadism is a clinical syndrome that results from the failure of the testes to produce physiological levels of testosterone (androgen deficiency) and an average number of spermatozoa due to disruption of one or more groups of the hypothalamic-pituitary-testicular (HPT) axis.

There are three types of hypogonadism:

Primary-testicular dysfunction leads to low testosterone levels and high levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH).

Secondary dysfunction of the HPT axis results in low testosterone, LH, and FSH levels.

Who should be tested for low testosterone? Mixed—manifests a mixture of primary and secondary hypogonadism and can be observed in older men. Very small or shrinking testes. Inability to father children; low or zero sperm count.

The more symptoms a patient has, the more likely he is to have low testosterone.   

The production of androgens in excess is a defining feature of hyperandrogenism (high testosterone in women), and testosterone levels have an impact on it. The most common clinical manifestation of hyperandrogenism is hirsutism, or excessive hair growth in androgen-dependent body areas. Other clinical manifestations of hyperandrogenism include acne vulgaris, weight gain, menstrual irregularities, and, in some women, polycystic ovary syndrome (PCOS) and acanthosis nigricans.

Measuring the testosterone level isn’t an easy task. Tests for free, bioavailable, and total testosterone are essential to help diagnose hypogonadism and rule out other conditions. For those who may be candidates for testosterone therapy and those already on treatment, testing can also help assess and monitor testosterone levels.  

This hormone can be bound to specific proteins in the body, and measuring it becomes problematic when it’s outside the normal ranges.

For example, it’s relatively easy to determine the exact testosterone level of a healthy man, but not that easy if he’s hypogonadal (has low T) and his testosterone levels are dangerously low.

More sensitive tests are required to measure low T concentrations in men, women, and prepuberty children.

Scientists and medical professionals have created some reliable testosterone-measuring methods.

These are called testosterone assays.


Serum testosterone tests (assays)

According to the dictionary, the word “assay” refers to testing a particular material, ore, or substance to find its composting ingredients.

Serum testosterone assay refers to accurately measuring the testosterone levels in the body of a male or female.

Accuracy is essential because it directly impacts the diagnosing a particular disease or health complication.

Endocrinology is the discipline responsible for measuring hormone levels in the body.

It encompasses a wide variety of assays that help the clinician confirm a diagnosis for a patient.

For example, testosterone assays are used to determine whether a male patient has hypogonadism.

Hypogonadism consists of reduced gonad activity. Men diagnosed with hypogonadism usually have low testosterone levels and experience different symptoms, such as low sex drive and gynecomastia (man boobs).

Testosterone assays are also used to determine if confident boys have delayed puberty onset and to diagnose androgen deficiency.

When circulating testosterone levels are very low, the sensitivity of some assays is diminished. That’s why picking the suitable testosterone assay is necessary to determine circulating T levels accurately.


Types of testosterone fractions in the blood

As shown in the figure below, about 2 percent of the testosterone in the body is active.  This “free testosterone” is not attached to binding proteins that would prevent it from interacting with its receptor.

About 40 percent of the body’s testosterone is attached to albumin. This is a protein that can release the hormone as the need for it arises in the body. Free testosterone and testosterone bound to albumin are “bioavailable testosterone.”

In a healthy young male, about 60 percent of his testosterone is attached to sex hormone-binding globulin (SHBG). Hormones bound to SHBG can’t be used by the body and lose their anabolic effect.  As males grow older or if an illness is present, SHBG sweeps up more and more testosterone, lowering free testosterone and its benefits.

Total testosterone is the sum of bioavailable testosterone and testosterone bound to SHBG. Measuring the total testosterone in the blood may not provide the whole picture and let you know how much “active” or usable testosterone you have.

Testosterone Bioavailable Free and Total

Types of testosterone tests

Measuring the testosterone levels in one’s body is not that easy.

One way to do that is by using Isotope dilution mass spectrometry. This assay measures total testosterone levels.

Laboratories also use direct chemiluminescent immunoassays. However, these assays are less accurate when testosterone concentrations are too low.

Liquid chromatography-tandem MS (mass spectrometry) and gas chromatography-MS are also used for more accurate results, mainly when testosterone levels are at the low and high extremes.

Measuring free testosterone is done after it has been separated from the protein-bound forms.

This can be done using equilibrium dialysis or ultracentrifugation.

Equilibrium dialysis is the most common method, and it involves introducing testosterone isotopes into a patient sample.

The free testosterone concentration is estimated based on the distribution of isotopes in the dialysis membrane.

The bioavailable testosterone can be measured using ammonium sulfate, which influences the testosterone bound to SHBG.

Assessing testosterone levels began approximately 30 years ago.

Tests were done on small blood samples, but their accuracy could have improved.

Current testosterone assays are more sensitive, require a smaller serum sample, and are more affordable. They can be done using nonradioactive methods in reference labs.


How is testosterone level measured?

Up to 98% of the testosterone found in the bloodstream is bound to proteins such as albumin and SHBG. Just about 2% is free.

Albumin-bound testosterone and free testosterone are known as bioavailable, and tissues can easily use them for androgen action.

On the other hand, total testosterone can be measured using nonradioactive immunoassay and chemiluminescent detection.

These methods offer accurate results if the male patient has testosterone levels in the normal range, such as 300-1000 ng/dL.

However, these assays recorded low testosterone limits of approximately 132 ng/dL, which is not customary in healthy men.

Clinicians have wondered why this happens and how they can improve the accuracy of testosterone assays when T concentrations are deficient.

Regarding total testosterone assays, the gold standard is a steroid-free serum interacting with gravimetrically-determined amounts of testosterone.

Independent measuring methods, such as liquid or gas chromatography with mass spectrometry, are also used.

Susceptible tests are necessary for women to determine total and free testosterone levels because women have much lower amounts of testosterone in the bloodstream.


Dr. Wang's analysis of testosterone assays

In a paper published in 2004, Dr. Wang and her colleagues compared multiple testosterone immunoassays (both manual and automated ones) with chromatography-tandem mass spectrometry.

The results were very accurate for the latter option, and the test was performed on serum samples from patients with different testosterone levels (ranging from under 150 ng/dL to 1,500 ng/dL).

This means that most of the automated and manual assays were accurate compared to LC-MSMS, but some tests provided inaccurate results.

The authors concluded that most manual and automatic testosterone immunoassays are ideal for differentiating eugonadal men from hypogonadal men. Still, they weren't accurate for women or children who haven't reached puberty yet.

It’s essential to notice that these automated and manual testosterone immunoassays are compared with gold standards of adult male reference ranges.

These ranges are set by individual laboratories and are usually monitored by the College of American Pathologists.

That’s why you’ll find several testosterone tests on the market. Getting the right one is essential to obtain the most accurate results.


4 Types Of Testosterone Tests You Can Buy Today

There are four different testosterone assays you can choose from to determine the amount of testosterone in your bloodstream accurately.


#1 - TESTOSTERONE Total and Free (Regular)

This test is ideal for people with testosterone levels in the normal range.

It measures total and free testosterone using direct analog/radioimmunoassay (for free T) and electrochemiluminescence immunoassay (for real T).

On the other hand, if you know you have deficient testosterone levels (hypogonadism and testosterone levels below 150 ng/dL) or very high testosterone levels (you are a bodybuilder with T levels over 1500 ng/dL). You might want to use the LC/MS test because it’s more accurate.

If your testosterone levels are very high, the test will show above 1500 ng/dL, not the exact number (such as 1,700 or 1,800).


#2 - Testosterone Free and Weakly Bound (Bioavailable Testosterone)

Bioavailable testosterone can be used for steroid-receptor interaction.

This test measures the amount of free and weakly bound testosterone in the bloodstream.

The test doesn’t look at the testosterone bound to SHBG because this type is biologically inactive as it has a high binding affinity.

On the other hand, weakly bound testosterone is usually derived from albumin and has a low affinity, which means that it can quickly dissociate and become available for interaction.


#3 - Testosterone, Free, Bioavailable, and Total, LC/MS (No Upper Limit)

This test has no upper limit for either type of testosterone, such as free, total, or bioavailable.

It uses more complex measuring assays such as liquid chromatography-tandem mass spectrometry to determine testosterone levels accurately.

However, this test is more suitable for bodybuilders, who are known to have very high testosterone levels.

If you are not into bodybuilding or think you have below-normal testosterone levels, this test is not ideal for you.

Other tests are more economical and can be used to determine your testosterone levels more accurately.

If you are on testosterone replacement therapy, you might want to choose a test that has no upper limit on total testosterone and up to 50 ng/dL limit on free testosterone.

An even more affordable test for people on testosterone replacement therapy has an upper limit of 1,500 ng/dL on total testosterone and a 50 ng/dL limit on free testosterone.


#4 - Testosterone, Total, LC/MS (No Upper Limit)

This test measures only total testosterone by liquid chromatography or mass spectrometry. This test is ideal if your testosterone levels are deficient (both men and women). It is also suitable for high testosterone levels due to TRT or bodybuilding. 

The test is the most accurate for testosterone concentrations under 150 ng/dL or above 1500 ng/dL for total testosterone.



Why should you test your testosterone levels?

Measuring testosterone levels has become increasingly popular nowadays, thanks to direct-to-consumer labs that are affordable and easy to use.

Males and females can buy one of the tests described above and determine the actual amounts of testosterone in their bloodstream.

But why is this a good idea?

First, if you have common testosterone deficiency symptoms such as fatigue or low sex drive, then measuring your testosterone levels is highly recommended.

This will help you decide whether a lack of testosterone is the problem and whether you should try testosterone replacement therapy.

Testosterone tests give you a broader insight into your hormonal health.

Secondly, if you’re on testosterone replacement therapy already, the test results might provide good feedback on your progress.

The clinicians who conduct these tests can give you valuable adviceLong-Term, such as how often to take testosterone gels or injections, whether you should reduce or increase the dosage, etc.

If you’re a bodybuilder, keeping your testosterone levels in check also helps you monitor your progress.

After all, testosterone is vital for muscle development, and if you have sufficient amounts of it, you’ll ensure muscle growth in the long run.

Testosterone is essential for women too. This hormone is linked to mental alertness, good mood, and increased sex drive.

Testosterone deficiency in women can also lead to low productivity at work and poor physical performance in the gym.

Numerous advancements in the medical field coupled with improved testing devices make measuring testosterone levels a more affordable and accurate process.


How to get a testosterone test?

Visit Discounted Labs, pick your favorite testosterone blood tests, and you’ll be able to get your results in a few business days.

You can also order other blood tests to check your glucose levels, cholesterol, triglycerides, blood count, and more!